[Normocalcemic hyperparathormonemia and articular chondrocalcinosis. Study of 69 patients compared to 57 controls]

The level of parathyroid hormone was measured by heterologue C terminal radio-immunological assay in 69 patients with clinical or radiological manifestations of the type seen in primary articular chondrocalcinosis. They were divided into three groups: P1 with undetermined clinical arthropathies; P2 with sub-chondral and arthosic arthropathies; P3 with radiologically definite chondrocalcinosis. They were compared with 57 control subjects broken up into four groups: T1 with chronic rheumatic arthritis, T2 with low back pain, T3 with primary hyperparathyroidism due to adenoma, and T4 with secondary hyperparathyroidism with renal insufficiency. A form of normocalcemic hyperparathormonaemia was demonstrated in more than one out of two patients in group P1 (15/29). It was seen in three-quarters of the cases in group P2 (12/16). And it was seen in more than a quarter of the cases in group P3 (7/24). This hyperparathormonaemia was statistically significant only in groups P1 and P2 compared to the normals in groups T1 and T2. The results we obtained in this study seem to be in complete concordance with those we obtained earlier in idiopathic hemochromatosis. This hyperparathormonaemia seems to regress with age and is often only discovered when the characteristic articular lesions have appeared. The discovery of normocalcemic hyperparathormonaemia several years before the appearance of the radiological signs of the disease would appear to be an important argument in favour of the diagnosis of early articular chondrocalcinosis. The existence of raised parathyroid hormone in primary articular chondrocalcinosis as well as in idiopathic hemachromatosis is special etiopathogenic interest even if there remain numerous questions concerning its origin and mode of action.